The overall objectives of this study is to assess the role of steroid sulfates in the mammalian testis in relation to the formation of biologically active steroid hormones. These studies include investigations on: 1) the distribution of 3 beta-hydroxysteroid sulfotransferase in interstitial and seminiferous tubules of the mammalian testis; 2) identification of steroids which form steroid sulfate conjugates in the mammalian testis; 3) the substrate specificity for the 17 beta-hydroxysteroid dehydrogenase from isolated interstitial tissue and from isolated seminiferous tubules; 4) examination of the in vitro regulation of 17 beta-hydroxysteroid dehydrogenase by gonadotropins and other peptide hormones. BIBLIOGRAPHIC REFERENCES: Wise, P.M., Payne, A.H., Karsch, F.J. and Jaffe, R.B. Cytoplasmic Oestrogen Receptor Complex of Female Ovine Pituitary: Changes Associated with the Reproductive State and Oestradiol Treatment, J. Endocrinol., 67: 447-452, 1975. Payne, A.H. and Kelch, R.P. Comparison of Steroid Metabolism in Testicular Compartments of Human and Rat Testes, in Hormonal Regulation of Spermatogenesis. Eds. F.S. French, V. Hansson, E.M. Ritzen and S.N. Nayfeh, Plenum Publ. Corp. N.Y., 1975,